1. Field of the Invention
The invention relates to a head plate holding a tube bundle having a plurality of tubes with a membrane, in particular porous, at one end and sealing them tightly.
2. Description of the Related Art
Tubes of said type, e.g., tubes, capillaries or the like made of a plastic, a plastic composite, optionally also with a laminar structure, made of a ceramic or a metal have a variety of applications.
For example, in the case of fuel cells, a fuel component is conveyed in such tubes of a tube bundle, which is why such tubes designed as a microreactor are regularly also provided with a membrane by which the fuel components reacting with one another are separated.
Another area of application of such tube bundles is for refining fuels of biorenewable materials, e.g., bioethanol. Bioethanol flows through a tube designed as a semipermeable membrane and the water present in the bioethanol is removed through the membrane.
In such tube bundles, there is fundamentally the problem of holding and sealing the tubes at one end. So-called potting or gripping of the ends of these tube bundles together and in particular also for a sealing connection with a housing, a pipeline or the like is usually accomplished by synthetic resin, e.g., epoxy resins, casting techniques, although these are not without problems. For example, the different thermal expansion coefficients at a working temperature of up to 150° C. in low-temperature fuel cells and/or up to 250° C. in medium-temperature fuel cells lead to substantial thermal burdens, which can lead to more cracks, leakage and the like in the area of the head plate, which usually results in failure of the entire apparatus.